1. Technical Field
Generally, the invention relates to a skimmer apparatus for recovering a less dense liquid which collects on the surface of a denser liquid. More specifically, this invention pertains to a skimmer apparatus which utilizes a moving loop having an outer surface that is preferentially wettable by the less dense liquid. Particularly, the invention relates to an oil skimmer apparatus which utilizes a skimmer hose that floats on the surface of a body of water to collect liquid hydrocarbon contaminants floating on the body of water and releasing the collected liquid hydrocarbons from the hose using a scraper.
2. Background Information
Oil skimmer devices are often used to remove oil and other liquid hydrocarbon contaminants floating on the surface of a body of water such as a water tank to reclaim the oil and make the water environmentally safe for reuse. For example, oil skimming devices are commonly found in the animal rendering industry to separate fat from water. Likewise, oil skimming devices are used in the machine tool industry to separate the waste oil that collects on the surface of the body of cooling water containing various non-oil lubricating agents used to cool and lubricate cutting tools during machining operations. In both industries, it is desirable to separate the fat or oil in order to recover and reuse the water or water with lubricating agents and to avoid environmentally unsatisfactory consequences of discharging fluids mixed with waste fat or oil. Such devices are primarily of a type which utilizes a continuous belt or a continuous hose having a surface which attracts or has a greater affinity for the oil or other liquid hydrocarbon than for the water, commonly called being preferentially wettable by the oil or other liquid hydrocarbon.
Oil skimmer devices which utilize a continuous belt have a lower end of the belt disposed within the body of water contained in a tank, from which the liquid hydrocarbon contaminants are to be removed, while an upper end is disposed outside the tank. A single motor-driven upper roller is typically used to drive the belt and a lower roller is at least partially submerged in the body of water. The liquid hydrocarbon contaminants adhere to the lower end of the belt as it passes through the liquid hydrocarbon contaminants and are carried upwardly to a wiper and/or a pair of squeeze rollers which removes the adhered liquid hydrocarbon contaminants which fall into a hydrocarbon collecting receptacle or a drain connected to a piping system.
For example, in U.S. Pat. No. 5,645,733 issued to Hobson on Jul. 8, 1997 a belt type skimmer for removing floating liquid hydrocarbon contaminants from surfaces of bodies of water is disclosed. The skimmer includes a housing and frame structure which is disposed above the body of water contaminated with liquid hydrocarbons. An idler roller and a pair of coating pinch rollers are rotatively mounted to the housing and frame structure for rotation about generally horizontal axes. An endless belt is looped over the idler roller, between the pinch rollers, and is suspended into the contaminated body of water for the liquid hydrocarbons to adhere thereto. A pair of scrapers are positioned on opposite sides of the belt at a position between the idler roller and the pinch rollers for removing hydrocarbons which have adhered to the belt. A collection receptacle is positioned below the scrapers to receive the liquid hydrocarbons scraped from the belt.
In U.S. Pat. No. 4,582,604 issued to Bashaw on Apr. 15, 1986 there is disclosed another belt type skimmer for removing floating liquid hydrocarbon and other contaminants from a body of water. The skimming apparatus includes a drive roller, and an idler roller having a star-shaped cross-section both of which are rotatably disposed in a spaced apart relationship in a frame disposed above the body of water. An upper end of an endless belt is extended over the drive roller and the idler roller with a lower end of the belt downwardly disposed into the contaminated body of water for contaminants to adhere thereto. One or more scrapers are connected to the frame between the drive roller and the idler roller engaging the belt for removing adhered contaminants. A pressure roller mounted to the frame biases the upper end of the belt into engagement with the drive roller providing friction to drive the belt. A collector is disposed below the scrapers to collect the liquid contaminants removed from the belt by the scrapers.
U.S. Pat. No. 3,640,394 to Brill et al. on Feb. 8, 1972 discloses a hose type skimmer for removing floating liquid hydrocarbon contaminants from surfaces of bodies of water. The skimmer includes a hose comprising an endless, substantially rigid loop of uniform circular cross section. The loop is gripped at an upper end thereof by a pair of opposed half-pulleys that move in opposite rotational directions to drivingly engaging the loop at diagonally opposite areas of the outer surface, one above and one below the center of a cross-section of the loop. The half-pulleys rotate the loop in a plane of its own passing a lower end thereof continuously into and out of the body of water for adherence of the liquid hydrocarbon contaminants. The adhered liquid hydrocarbon contaminants are removed from the loop into a receptacle by squeezing out upon passing through the half-pulleys, by using a hose engaging scraper, or by a blast of air. The lower end of the loop may oscillate up and down by the loop pivoting about an axis tangential to the loop at the half-pulleys. A modified version of the loop has a brushlike surface and a mating surface on the half-pulleys.
An improved type of oil skimmer utilizes a toothed drive pulley and a smooth guide pulley rotatably mounted using a pair of parallel shafts mounted to a support frame disposed adjacent and above the body of water with hydrocarbon contaminants. The pulleys engage an upper portion of a flexible skimmer hose which extends downwardly and horizontally floats on the surface of the body of water. The pulleys are driven by a motor and gear box combination to continuously move the skimmer hose. A vertically disposed fixed hose scraper disposed between the drive and guide pulleys engages the skimmer hose to remove adhered hydrocarbon contaminants therefrom which fall into a receptacle disposed therebelow. A removable safety housing may be attached to the support frame to shield the rotating drive and guide pulleys from interaction with persons during use.
Although these skimmer devices are adequate for the purpose for which they were intended, they have substantial drawbacks. The belt type skimmer devices are rather complex and reintroduce the floating contaminants into water by dragging the material back into the waste stream. The belt type skimmer utilize belts which are prone to breakage and are rather expensive, and the belt and other component parts must extend below the surface of the water which increases the likelihood of damage to the skimmer device. The hose type skimmer device requires extensive time and expense to replace broken toothed parts of the drive pulley and the whole guide pulley as a result of normal wear and tear. Also, the complete drive and pulley guides are sized to fit only one size and cross-sectional shape of skimmer hose. To change the drive and pulley shape to accommodate a different size and cross-sectional shape of skimmer hose would again require extensive time, expense, and engineering expertise. The shape and position of the skimmer hose scrapers are fixed and can only accommodate one size and cross-sectional shape of skimmer hose. The hose scrappers cannot compensate for variations in the position of the skimmer hose during operation resulting in ineffective scraping of the skimmer hose. The safety housing can be removed from both the belt and hose type skimmer, with the skimmer belt and hose still being drive, resulting in a hazardous safety condition.
Therefore, the need exists for an improved oil skimmer device having a drive pulley and a guide pulley that are quickly replaceable and which accommodate skimmer hoses of different cross-sectional sizes. The oil skimmer device needs adjustable scrapers to permit compensation for variations in the position of the skimmer hose during operation. The oiler skimmer device needs a safety housing which stops the skimmer hose when the safety housing is removed to prevent personal injury.